fn main() {
    fn aa(a: i32, b: i32) -> i32 {
        a + b
    }
    let mut a: &str = "123";
    println!("a is {}", a);
    a = "11111";
    println!("a is {}", a);
    println!("aa is {}", aa(1, 2));

    let number = 10;
    if number % 2 == 0 {
        println!("number is {} even", number);
    } else {
        println!("number is {} odd", number);
    }
}
